Acid-catalyzed olefination of bio-oil in the presence of ethanol

摘要

Background: Upgrading of bio-oil using acid-catalyzed olefination with added alcohol was explored. The previous approach of using a reagent such as 1-butanol to overcome the phase separation problem demonstrated excellent results. However, bio-based production of 1-butanol is still a low-yield process. In this work, a low-cost commodity solvent and reagent, ethanol, was used. Also, ethanol has lower viscosity than 1-butanol. Results & discussion: Bio-oil was reacted with excess 1-octene in the presence of solid acid catalysts and ethanol. Acid-catalyzed olefination induced changes in the resulting bio-oil by generating variety of alcohols, ethers, esters and oligomeric mixtures of the starting olefin. The reaction also decreased the water content and acid value, and increased the heating value of the bio-oil. However, the increase of the high heating value of the product bio-oil was moderate due to the presence of two phases in the reaction mixture. Conclusion: Ethanol is not as effective as less-polar 1-butanol at promoting 1-octene and bio-oil phase compatibility. This study shows the need for a low cost, better reagent than ethanol. The reagent should effectively decrease the phase separation to facilitate the reaction between bio-oil and the olefin. Solid acid catalysts with high hydrothermal stability are also needed to improve the upgrading process.